r _par excellence_. Through digestion and assimilation the
physiological process takes up the food, juices and gases, to support
and augment the life of man. The pathological process, on the contrary,
because the conditions for nutrition are ignored, reverses the
upbuilding processes; and the organs of life wither, waste and weaken,
until life goes out like fire unfed.

Man has been slowly learning to take sanitary measures in reference to
everything that contributes to comfort in his surroundings, and
hygienic measures in reference to everything conducive to stability in
his health.

Through ages he has learned, by experience and experiment, of the
changes that inevitably occur in such perishable nutritive substances
as water, milk, meats, vegetables, fruits, etc., if they be left
uncared for; and he has been led thus to the inference of the law of
decomposition--or putrefactive and fermentative changes. Idle
substances, like idle minds, have decomposition and the devil for
companions. Substances confined in containers open to the air--ponds,
cesspools, etc.--are every-day object lessons to man of the fact that
the chemical changes they undergo furnish the conditions for breeding
bacterial poisons, and that these poisons are a dread menace to animal
life.

If the reader will observe the analogy between the decomposition of
substances in vessels or pools, and the decomposition of food in the
reservoir called the stomach; and its further decomposition in a long
canal (the small intestine), connecting the stomach with other
receptacles called the colon and sigmoid flexure; and then the
decomposition of _their_ contents; he will readily comprehend the
chemical putrefactive or fermentative changes or bacterial action that
take place in the organism, if for any reason the contents be confined.

Of the four chief elements that enter into the composition of living
bodies three are gaseous, or convertible into gas. In the physical man
water constitutes three-fourths of the weight of the body. This being
so we realize why, notwithstanding our sense of solidity and weight,
chemical changes occur quite as readily in our organism as in the
substances we see about us. There are no waterproof walls in the body
of man to impede the percolation of liquids freighted with promiscuous
Passengers from the alimentary canal; Passengers designed to nourish
the organs for which they have an affinity. But there are those that
have no organ